High-quality ventilation pipe 4H0121081AB for A8/S8

High-quality ventilation pipe 4H0121081AB for Audi A8/S8 D4
This coolant expansion tank ventilation pipe with OE number 4H0121081AB is an OEM-spec cooling system spare part exclusively for Audi A8 / A8 Quattro / S8 D4 chassis (2013–2018), matching 3.0T TDI diesel engines. It serves as the breather tube connecting the auxiliary coolant reservoir to the main cooling circuit, discharging internal air and balancing system pressure.
Core Selling Points
Market proven hot-selling replacement part
It is a frequently replaced cooling pipeline fitting for Audi D4 A8/S8 diesel models. Repair shops and auto parts wholesalers keep stable repeat bulk orders due to large aftermarket maintenance demand, bringing steady sales volume for distributors.
OE-standard precise matching
Manufactured strictly following factory original drawings. The integral pipe bending curve, total length, dual-end quick-lock connector size and assembly positioning angle are fully consistent with genuine OEM parts. Direct plug-and-play installation without cutting, bending or modification, perfectly matching the expansion tank interface of D4 chassis.
Reinforced high-temperature resistant composite material
Adopts modified nylon hard pipe + built-in EPDM sealing ring integrated molding. Outstanding resistance to high-temperature coolant corrosion, anti-aging, anti-cracking and anti-deformation; maintains stable sealing performance under long-term high-load engine operation, adapting to all climate and road conditions.
Integrated leak-proof quick connector structure
Equipped with original-style snap-on quick plugs at both ends, thickened embedded rubber gaskets block coolant leakage and air intake into the cooling loop. One-piece seamless pipeline eliminates intermediate joint seepage risks, greatly extending service life.
Effectively repair common cooling system faults
Perfectly fixes slow coolant loss, frequent engine overheating, air blockage inside cooling pipelines, persistent high-temperature warning lights and coolant residue seepage around the auxiliary kettle, restoring balanced pressure circulation of the whole cooling system.
Rigorous quality testing & reliable supply
Every ventilation pipe undergoes high-low temperature cycle aging test, coolant soaking resistance test and hydraulic pressure leak test to guarantee stable sealing performance. Mass ready stock supports fast bulk shipment. Custom neutral packaging and private label services are available to meet cross-border wholesale demands.